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Why are the throttles of aircraft such as the Twin Otter placed on the overhead panel?
Some aircraft such as the DHC-6 Twin Otter, have their throttles on the overhead panel:

Is there a reason that they are not on a center console between the pilot seats or mounted to the panel like on most airplanes?
It seems like it would be more comfortable for the pilot if he didn't have to reach up to change the power settings.

What I think I would find objectionable from what I see in the image is that the throttles are off-center in favor of the left seat. Seems like it would be quite a reach from the right seat, especially for a short f.o. Great pic, by the way, makes me very much wish I was still flying.

The first explanation I thought of for the overhead location, is if the seaplane took on water. I saw such comments elsewhere as well. However, as mentioned in the question, the other standard location for throttles is not the floor where water from the sea would be a problem, but the panel or a console above the floor. So I'm putting this as a comment instead of an answer.

Because the space where the throttle quadrant would be on most aircraft is taken up by the control column.

I think it was for two reasons:

It makes for a straight path for the controls to reach the engines, as all of these are fly by cable. Many of these aircraft where also designed for harsh climates, so I imagine it's an advantage to have fewer pulleys and other things which might rust and require maintenance.
There is very little space to place the throttles further down, especially with the control column mounted on the DHC6 Twin Otter where it is. If you did want a pedestal, you'd have to separate the control columns, requiring further mechanical components, and you'd have to route the engine cables upwards, both of which would be undesirable.

As you mentioned, there are downsides. Commonly mentioned ones are:

It is not particularly comfortable to have you arm raised for an extended period of time, and you lose some sensitivity in it.
You hope that the other pilot used his deodorant that morning.

Other somewhat similar aircraft which use this configuration are the PBY Catalina and Grumman Goose. Another one is the Avro York heavy transport aircraft.

Lol at the deodorant. Flaps, check. Captain deodorant, check. Throttles... :D

Overhead throttles are a pretty common thing in seaplanes (see the picture in Manfred's answer).
This actually came up as an EAA Young Eagles FAQ and in addition to the reasons Manfred gave the Grumman engineer they spoke to gave an explanation I'd not heard before:

…first and foremost, the reason the throttle are overhead is due to a physiological issue related to the g-forces encountered during water landings. At times, forces as high as 3 Gs can be registered on contact with the water, and by having the throttles hanging down from a pivot point above, it's nearly impossible for the hand of the pilot to bend the throttle.
  When the downward force is encountered, the pilot's hands will move downward as well, so the force is applied to the throttle in a way that will not damage the linkage, and it will not likely result in an abrupt throttle position change. With a panel mounted throttle, it's likely that a higher-G landing on the water (or on the deck of a carrier) would result in a bent throttle.

This is an interesting explanation, but I'm not quite buying it. 3Gs even for a water landing sounds like a lot. If you have a hard touchdown on the water your hand would move down, and you might risk loosing the grip of the throttle if it caught you off guard. If it would actually be a problem with the strength of the throttle levers, I think it would be a straightforward process to strengthen them...IMHO :)

@Manfred I'm not entirely sure I buy bending the throttle either, but if you catch a wave on a water landing I could definitely see that being 3Gs or more in deceleration forces - It can be a good jolt in a boat, and there you have the benefit of being at 0 feet and a lot fewer knots. I think (no seaplane experience) that the impact of such a landing would tend to knock your hand away from the overhead throttle (as opposed to a traditional push/pull or quadrant where the impact would send your hand forward, advancing the throttle, which may not be what you want)

More likely, it would be to prevent inadvertent movement of, or losing one's grip of the throttles in the case of a rough landing. Must be a real issue, because many (but not all) aircraft capable of water landing have overhead throttles. I was looking at a cockpit photo of a Sikorsky S43 (the one once owned by Howard Hughes), and it had overhead throttles. In the case of the  twin Otter, I have to wonder if this wasn't held over from the single engine Otter, which is often float equipped.

In the case of a high wing multi engine plane, like the Grumman seaplanes, the distance and a less convoluted path for a steel cable from the throttle control to the engine may have a lot to do with this design choice.  However, this is a guess completely unencumbered with facts.....

"completely unencumbered with facts" - awesome!

If you look at something like the Grumman Widgeon, Consolidated PBY, or even single-engine seaplanes like the Lake family of amphibians the placement of the engines certainly makes this seem like a reasonable explanation :)


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Are pilots armed?
Are pilots armed to defend themselves in event of a terrorist attack? It seems that in view of terrorist attacks and hijackings since 9/11 they would be.

Some pilots are armed, like casey says. Most, however, are not. And they have very little reason to:

After 9/11, a lot stricter security measures have been made on all airplanes to limit the access non-essential staff has to the cockpit. This includes measures like a reinforced locked door between the cabin and cockpit.
Because of the improved measures, terrorists these days are less inclined to use the plane as a weapon, choosing instead to use bombs in their shoes, underwear or carryon luggage to detonate the plane.
A gun on a plane can be dangerous, especially in the cockpit. it can hit vital instrumentation, damage the fuselage or a window, or cause friendly fire.
In the confined space of an airplane, some self-defense training is likely to be more useful than a gun. in addition to collateral damage, a gunshot can cause the passengers to panic. An assailant can also steal the gun, giving even more cause for concern.

@DavidRicherby Is the Mythbusters link broken?

Note that, as shown by Mythbusters, putting a bullet through a plane window does a whole lot of nothing much at all.

@DavidRicherby indeed, the hole provided by the outflow valves is far bigger than a bullet hole.

Note that Mythbusters was debunking the "Explosive decompression" myth. Note also that this answer makes no mention of explosive decompression. You're tilting at windmills here. As seen on the show, shooting a window does still do significant damage to the window, damage which in the cockpit can obscure the pilot's visibility. I'd call that dangerous.

@JonathanVanMatre Sure, it causes damage and, sure, landing the plane without that damage would be safer than landing it with. However, the damage is by no means disastrous and you need to consider the baseline. If you're seriously considering firing a gun in the cockpit, the situation must be pretty seriously bad. If you manage to end that situation and the only cost to the aircraft is that you can't see through the whole of one of your windows, that probably means you've got yourself into a much safer place than you were in before you fired the gun.

I wasn't referring to explosive decompression. what I was referring to was that if a window loses a lot of structural integrity (say, after a bullet hole), the window might be damaged even further if there are harsh enough winds. Also, a gun is mainly useful at range, and I doubt a hijacker could get any decent ranged weapon on board a plane, so they will likely attack you at close range.

You also need to take into account that you're unlikely to be prepared for a hijacking. By the time you noticed something is wrong, processed that you are under attack and have readied your gun (stand up, reach down, remove from holster, remove safety, aim), your assailant has had time to stab you. If you don't need to ready your gun (just stand up and prepare to defend yourself), you gain a few precious seconds. I believe you don't have more than 2-3 square meters in a cockpit, which is too confined a space for using a gun effectively, one would assume.

@DavidRicherby Entirely valid point, and now you're giving OP the respect of addressing his argument directly. Look at the dialogue that ensues when you aim your lance at real dragons. ;-)

@JonathanVanMatre Thanks for the praise but, actually, my lance was true all along. The strawman was entirely yours: I never said anything about explosive decompression. The video could have been addressing a myth that shooting through a plane window would cause a plague of locusts and it wouldn't have altered my point: nothing much happens when a bullet goes through an aircraft window at altitude. (Also, it was more a small informational sign than a lance.)

Don't misunderstand me...said praise was in no way faint. This is a far more interesting angle on the topic: where is the balance between the potential risk to the plane and the potential risk of not confronting an attacker storming the cockpit? If you harm the plane you imperil everyone on it, but how likely is the plane to be harmed? If you fail to harm an attacker bent on destroying the plane, you imperil everyone on it, but what if the attacker's intent does not include immediate peril to those on the plane? I'd be very interested in knowing how a pilot makes those choices.

@JohannesPille Since 9/11, all hijackings involving intrusion into the cockpit have been with the aim of landing the plane somewhere else, not something terrorists usually do. I have not heard of a single hijacking aimed at using the craft as a weapon, only as leverage. Meanwhile, a number of plots involving bombs in carry-on luggage, shoes, underwear or other places have been intercepted and defused. A hijacking is still dangerous, but it happens less in commercial craft lately than attempts at bombing an aircraft. 9/11 is still an isolated incident, however horrible it was.

@Nate, I was not contending that at all. 9/11 most definitely was an isolated incident indeed. However, how often was a bomb in a shoe found or used, for instance? How many planes have been blown up in the past 10 years? How often has it been tried? There is no threat. Is what I'm saying.

@NateKerkhofs That's also a lot of hijackings before 9/11. Really, most hijackings have included "land the plane elsewhere" among their demands, where "elsewhere" is a place the hijackers think won't have them arrested. For that matter, hijackings like that can be done through the threat of explosives, so it's all mixed.

@JohannesPille Last 10 years: Wiki lists 6 attempts, 2 of which brought down their targets (and one of those had 2 planes attacked, so 3 planes brought down in the last 10 years). In the 90s, there was 1 successful bombing, which was a test run to a failed large-scale plot; in the 80s, there were 9 resulting in deaths.

Some are -- in the US.  The TSA has a program called Federal Flight Deck Officer (FFDO) that involves training from the US Federal Marshals.  The pilots who participate in this program are armed but will not display that status when in view of the public so you will normally be unable to identify them.

The problem with a gun is that if staff are the terrorists then everything becomes that much more dangerous.
In some cases such as FedEx hijacking, and other ones, the chance of the hijacking being an inside job is higher. Therefore it was much more easier to overpower one hijacker who wanted to assault crew physically, than it would be if he were carrying a gun.
Guns usually make things much much worse.
EDIT: Even if the pilot has a gun. It still gives opportunity for the hijacker to snatch the gun. Pilots are usually busy flying the plane rather than constantly inspecting who is behind them and having a gun on the ready. And if the flight is a long one and pilot retrieves into the bed to sleep then likelihood of having the gun snatched is even higher. And if you look at some hijackings, the hijacker usually has the jump on the victims, so him obtaining a gun would not be too difficult.

Yet if the pilot, who is already in control of the aircraft has a gun, it really doesn't make him much more able to hijack the plane, now does it? It would be a different matter if we were talking about stewards, and in that case I'd agree, but we're talking about pilots here

in case of the FedEx case, had the other crewmembers had guns to control the situation, the attempt would have been over a lot earlier. It was because the hijacker had an axe and the person trying to control him was unarmed that it took as long as it did.

For anyone that hasn't seen it, the Air Crash Investigation/Mayday episode on this flight is worth watching:  https://www.youtube.com/watch?v=IQcNxESf-Ho

@jwenting if pilots had a gun, then instead of him using an axe, he would have changed his plan to snatch pilot's gun rather than charge in with an axe. And then a desperate man with a gun will be more reckless in his shooting than pilots who would try not damaging the plane and plunging to their fiery death.

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What happens to the ejection seat after a pilot ejects?
When a pilot ejects, what happens to the ejection seat? Does the pilot stay in the seat until he lands, or does it get disconnected from the pilot somehow?

Not directly related, but to add more info.  The survival pack on many seats dangles below the pilot on a line.  The pack is normally stored in the seat pan and is attached by a lanyard to the pilot's harness.  As it is dangling, the pilot can feel it's weight pulling down.  At night, or in a water landing, this also assists with judging the landing as when the pack hits the ground, the line goes slack and you have about a second to go before contact.  You might find this interesting. http://www.youtube.com/watch?v=e-RcMEDLu7Y

I should have added that the pack is actually part of the seat cushion.  The pilot sits on it.

@Simon That video makes it clear just how violent the acceleration is.  I couldn't tell from the video what happens to the seat, however.  Of the two dangling bits, one is seat shaped--is that the seat pan?

It depends on the seat. Most modern seats, including the ACES II system common in US Fighter Jets, fall away from the pilot at a pre-determined altitude. [src]

Once out of the plane, a drogue gun in the seat fires a metal slug that pulls a small parachute, called a drogue parachute, out of the top of the chair. This slows the person's rate of descent and stabilizes the seat's altitude and trajectory. After a specified amount of time, an altitude sensor causes the drogue parachute to pull the main parachute from the pilot's chute pack. At this point, a seat-man-separator motor fires and the seat falls away from the crewmember. The person then falls back to Earth as with any parachute landing.

Generally, according to that link, this occurs at just over 100-200 feet above ejection height. However, if you eject at high altitude, such as Captain Scott O'Grady did (26,000 ft), the seat will fall away on a sensor (either 10,000 or 18,000 feet, I don't recall which). The chute may open automatically, or if it is not set to at that height, you can then pull the chute manually, or wait until its set height to open.

Do you happen to know if survival supplies are ever attached to the seat so the pilot can survive behind enemy lines? (Ammunition, MRE's, rifle, maps)

This is from a US Military perspective, but pilots rarely have rifles. They will usually have a pistol in combat zones, but that is on their person. From what I've read, the primary survival kit is under the seat, and when the seat falls away, it dangles below you on a (fairly long) line. This would contain some food supplies and more survival gear. I believe there is also a smaller survival kit closer to the pilot on the line, or connected to them, that has detailed maps and basic supplies. Of course, the pilot would also have many maps instantly accessible.

Ah, ok. Any idea why a carbine couldn't be attached on that line as well? It seems that it would be better to be behind enemy lines with a rifle than a pistol...

It's not that it couldn't, just that there's not much point. In general, surviving behind enemy lines depends on concealment and speed. A pistol is a last resort anyway. A rifle just adds weight and bulk and is probably too tempting to use, and would give away your position easier.

I recall reading a long time ago that Capt. O'Grady manually cut away his seat after freefalling for quite a while...which would seem to point toward 10,000.  I may very well be mistaken though.

@SteveV. - it may be. I do know he manually pulled the parachute, but I thought I remembered the seat falling away on its own from a book I read. But it's been years since I read that, so my memory could easily be in error

I was in the Med and we were called to the Intel vault for an Air Wing brief. We were preparing to go to war the next morning with a predawn launch attacking multiple enemy naval bases. The strike lead said at the end of the brief, "Go back to your bunks and go to sleep. If you wake up and the clock says 0800 we didn't go to war." Some of the JO's mentioned they wanted pistols from the Armory. The Vets from Vietnam told them they were better off with out the weapon. As it turned out the war didn't happen.

I ejected from an FJ-4 at 17,000 ft at 410 kts IAS. I was very briefly unconscious.
When I woke up I was head down and looking up between my legs at an object drifting away from me which I saw as my parachute back pack. I could see the tabs down each side side of the pack as well as the pin attached to the D ring. I fell  about 13,000 feet before I looked at the D ring. I occurred to me that I might as well pull it even though I still thought I had somehow lost my chute. I felt a minor shock and looked up to see my parachute open. Then it dawned on me that the object I thought was my back pack was the ejection seat. As I remember separating from the seat was simply a matter of the pilots body and the ejection seat having differing response to the wind experienced after ejecting.This incident took place in July of 1957. My back will probably quit hurting before many more years.

A) Thanks for serving. B) Glad you survived. C) What was it that disconnected the belts holding you into the seat?

Holy Toledo! Nice to know you survived.

My only reference is a T38 flight manual I happen to have. That seat has a "man-seat separation system" that is a separate pyrotechnic device that unlatches the straps holding the pilot to the chair after clearing the aircraft. (The pilot wears the parachute, which nestles into a cavity in the back of the seat.) The manual exhorts the pilot to try to manually disengage from the seat, but says that the man-seat separation system can rarely be beaten. There's nothing in the manual that says the seat has a separate chute of its own.

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What is a counseling session with the FSDO/FAA?
I just flew into Bravo unintentionally 48 hours ago. My error: I thought I was 1,500 feet above the ceiling, but I was 1,000 feet below it.
Furthermore, I had an incorrect frequency for Approach, and while I eventually found the proper frequency (I'd planned to request flight following) I had crossed over the outer ring.
When I contacted Approach, the Approach Controller explained I was in Bravo, and to turn West and exit. I did say, "Am I not ABOVE Bravo airspace?" He said "No, you're in it" and to fly West and exit.
From that moment, I followed approach control's directions to a T, but could not understand why he directed me West (remaining in Class B for 13 more miles) instead of having me climb 1,500 feet or angle back North or North-West to exit Bravo more quickly.
I was given the dreaded phone number, made the call after landing, had a friendly enough discussion, and he said it would probably lead to a counseling session. My question is what is that?
I'm familiar with the remedial training option the FAA may offer, but what did he mean by "counseling session"? The controller implied it would be handled by phone.
I'm not freaking yet, just concerned. I told everything that happened on that phone call, and then filed an ASRS report.

While this doesn't answer the last part of your question, have you seen this: I just flew into class Bravo airspace without a clearance! Now what??

The controller probably sent you west because it was the most convenient/logical thing to do looking at the scope - there may have been other traffic he was working that needed to be where you would have been in a climb or on a northerly heading, and if I had to guess I'd say "West" was probably a nice empty area of sky to put you in while recovering from the surprise of having you show up on the scope without a radio call :)

I think the "why West?" question is surprising (hopefully "they're" not reading this or it will be another phone call :) )  Of course, there are a million and one reasons ranging from policy, KISS, a thousand other activities going on that you didn't know about, and more -- why the controller would give that particular exit route.

A "Counseling Session" is the lightest slap on the wrist the FAA can give you (aside from doing nothing).
Basically it means "you screwed up, you know you screwed up, and we (the FAA) know you know you screwed up" -- they just want to sit you down with someone from the FSDO (probably a FAA Safety Team representative) and have a conversation to make sure everyone is clear on what happened, how the violation happened and that you know how you can avoid this sort of thing happening in the future.
My understanding is that counseling sessions are "informal" (they're not an official "administrative action", so I'm pretty sure they don't go on your airman record) - the FSDO will note that they talked to you and bury that tidbit in their internal file, to be generally forgotten unless you decide to make a habit of busting airspace.
(The closest "official documentation" I can find on counseling sessions is in the FAA Safety Team's Representative Manual -- Page 12 if you're interested.)

Some things to bear in mind:

You're the kind of pilot the FAA isn't out to beat up on.
Yes, you screwed up - but you know that and you clearly want to make sure you don't do it again, which is really all they want too.
Make sure you're clear in your mind what happened & how to avoid similar incidents in the future.
Did you misread the chart? The altimeter? Get distracted looking up the frequency? Something else?
Don't admit to any other violations during the counseling session.
(Presumably you didn't commit any, you got a proper flight briefing, etc.)
Hang on to your ASRS strip.
You won't need it for a counseling session, though mentioning you've filed an ASRS report won't hurt anything. If the FAA opts for a more formal action that strip is going to be important.
If you have AOPA pilot protection services now would be a good time to chat with them too, just to cover all your bases.

Thanks, Vortaq7.  Much appreciated.  So ... the approach controller and others I've spoken with say a counseling session is a phone call.  I realize your comment "sit you down with" could be a figure of speech.  Are they also done in person?

And now it is done.  I had my counseling session with a very reasonable and professional safety inspector yesterday.  It was indeed handled by phone, and he assessed that I had done my homework since the time of the incident to prevent a similar situation from ocurring.


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Are there any civilian planes with seating arranged in a round area?
Recently, I heard Airbus want to make an aircraft that looks like a UFO.  Is there currently any civilian passenger plane designed with the seating in a round area rather than the traditional design with a long aisle?

If you take a look at helicopters and blimps you'll get something closer to that, but essentially no.

it's a flying wing design, the major challenge (besides the getting it flying part) with that is internal layout because you don't have a straightforward central cylinder where you can stuff the pax

When I used to fly from San Paolo to Rio, the shuttles they used had a semi-circular seating arrangement in the last few rows of the cabin (and no galley).

On some first class 747s that flew in the 1970s, the upper deck had circular seating (around a bar and such).  I don't know if any of those cabin layouts are around today.

@user19555: Yes, Qatar Airways has a lounge in their A380's. See http://www.qatarairways.com/global/en/airbus-380-experience.page

The simple answer is no.
Why a round seating design is not feasible? We need to look at a few aspects.

Real Estate
An airplane fuselage is rectangular (roughly speaking) in shape (when viewed from top). Airplane seats are rectangles. If you place rectangular boxes in a circle, you can fit lesser number of boxes than if you place them in a rectangle of the same area.
Airlines have just one goal to achieve, i.e. make money. Yes they take people from point A to point B too but if demand arises for joyrides, airlines will not be hesitant to start that.
By fitting more people in lesser space (not in inhumane positions mind you, governments don't allow it), they make sure that their profits soar.
Loading/Unloading Passengers
In a circular configuration, people will be a lot more confused to find their seats. People are already so confused and disillusioned when boarding a regular airplane that flight attendants have to guide every single person about where the seat is. Don't believe me? Notice how the flight attendant will snatch the boarding pass from your hand if you try not to show it.
Servicing Meals
Trolley carts used in airplanes are designed for straight aisles. In case of circular aisles, it would be very hard to maneuver them because flying airplanes do get bumps every now and then.
Evacuation
In case passengers need to be evacuated, a circular design would not be very practical. Since all people will not facing forward, simple emergency instructions, e.g. move to the front/back/left/right of the airplane can be confusing and will waste time. Locating an emergency exit will be harder too than in a normal airplane.
History
People are used to the conventional design. The present design is in use for over half a century. In addition to airplanes, trains, buses, cars and buggies have the same configuration.

I am not sure how that (and some other) news channel found about Airbus's new design. Airbus does disclose the future innovations it is working on, and flying doughnut is not mentioned there. It could be that is it on paper only at the moment. The patent information mentioned in your referenced article cannot be found with United States Patent and Trademark Office, or at Google Patent Search.

In my experience, on single-aisled planes, the attendants usually let people find their seat on their own; on wide-body jets, it makes sense to direct people down the correct aisle. Sometimes, they do demand to see boarding cards on boarding: my impression is that this is usually when boarding wasn't via a jet-bridge so it's possible that people will try some kind of switcheroo.

"I am not sure how that (and some other) news channel found about Airbus's new design." Because Airbus filed a patent on it. Filed patents are public knowledge.

@DavidRicherby I couldn't find that patent here or here. That's why I cannot confirm about it. Do you believe everything you see on TV?

http://worldwide.espacenet.com/publicationDetails/originalDocument?CC=US&NR=2014319274A1&KC=A1&FT=D&ND=3&date=20141030&DB=EPODOC&locale=en_EP

A number of executive / private jets have club-style seating. If you are not concerned about passenger density you can arrange the seats any way you want. I used to skydive, we would sit on the floor in any reasonable pattern depending on the plane size and load.
However, in commercial air travel you will not find any wasted space outside of a concept drawing. The original 747 designs included using the entire upper deck as a lounge. Didn't happen in reality as the loss of revenue seats was too high.
So, sadly, circular seating looks neat on paper, we won't see it in reality unless it's our private plane.

There are no current passenger planes that use the circular seating layout.
However, they are certainly being considered by airline manufacturers.
One of the main reasons, as cited in the text of the link you provided is that "the design will address the ongoing problems associated with pressurised cabins that places [sic] stress on the front and back end of planes requiring heavy reinforced frames."
Furthermore, when seating is organized in a circular fashion, the maximum distance between any two seats is dramatically reduced.  This can help improve passenger and employee foot traffic onboard the aircraft.  Food service can be enhanced as well as ability to quickly access a restroom.  More options for accommodating disabled passengers become possible.  Access to emergency exits can be improved when compared to a traditional seating arrangement.
Another reason for circular seating layouts is that they are often a part of designs that do not incorporate windows.  By removing the windows, the plane can be made lighter and more efficient.  All the structural reinforcements required for the windows can be removed.  Another example of a windowless design can be seen here.
Even with the amazing digital screens that can be incorporated in a windowless design, I personally feel that one of the best parts of flying is the direct unadulterated view through the windows.  I hope future designs ensure that passengers are always able to enjoy that unique experience.

I never saw any since I am born. I am 47 years old. In a business section, you can have rotating seats; but usually it is two seats facing two other seats. In Air Force one, I saw some pictures where the President of The United States is seated at a desk; I would remove that for safety issue.

We prefer answers based on data rather than personal anecdotes. Also, Air Force One is a military plane, which is specifically excluded from the question.


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Where to find information about aircraft type knowing the flight number and date?
Having flight date and exact flight number, I would like to know aircraft type (like Boeing 737-400). Is there any service where I can get such information in bulk (for hundreds of flight dates and flight numbers)? I know that flightradar24 provides us with similar data, but it doesn't have any API to get such information for many cases.

You are looking for the aircraft model, not the aircraft name.

@Federico also known as the aircraft type :)

@Federico, what is aircraft name then? ;)

to make a not-so-well-know example this B-29 was named "Enola Gay"

Side note: I believe KLM name (all?) their planes. List. Example: "City of Lima" @Federico

@GlenTheUdderboat afaik, all commercial companies name their planes

@Federico, I'm fairly sure plenty of US carriers do not. It does seem pretty common in Europe, though. Icelandair does, as well, for example.

FlightAware will give you all the info and has an API.


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Would the flyby in this video be illegal under 91.119(a)?
I was watching this video

 and just curious about the legality. Would it just fall under 91.119(a) operation of an aircraft 'anywhere'

Well if I ever saw something reckless, then this is it. I know 91.13 is a catch-all if-we-don't-have-anything-else-we'll-use-this, but in this case it would appear quite appropriate.

I also have my doubts.  The dude in white has pretty long hair and there's no apparent downwash as the aircraft goes overhead.  http://amasci.com/wing/lasrWing.gif  (Sidenote, I will take any opportunity to use this gif.)

Legality aside this looks 100% fake.

This depends how you look at it but there are definitely some FARs this guy is in breach of. First one that comes to mine is 91.119 on minimum altitudes, it's pretty straightforward (assuming this is an area other than congested area)

Except when necessary for takeoff or landing, no person may operate an aircraft below the following altitudes:
(a) Anywhere. An altitude allowing, if a power unit fails, an emergency landing without undue hazard to persons or property on the surface.
(c) Over other than congested areas. An altitude of 500 feet above the surface, except over open water or sparsely populated areas. In those cases, the aircraft may not be operated closer than 500 feet to any person, vessel, vehicle, or structure.

He is pretty clearly within 500 ft of that person...
You can see that there is a case for sparsely populated areas but I would argue that if there is a backyard party going on this is not a sparsely populated area.
Then as mentioned there is the catch all in.13

§91.13   Careless or reckless operation.
(a) Aircraft operations for the purpose of air navigation. No person may operate an aircraft in a careless or reckless manner so as to endanger the life or property of another.

I'd say that's reckless but of course that's up for debate. Then again it's impossible to say where this happened so we can't know what type of airspace this is in and if there were possible issues there. I would go on to say that at an altitude that low I would turn on my landing light to increase awareness and enable me to see the ground better.
If you really want to push it you could even go as far as saying that maneuver is aerobatic flight since it's an abnormal attitude (at the altitude it's being performed) and most likely not seen in normal flight. For the record that attitude looks to be about around 30 degrees which would be a standard steep turn (something I would never attempt that close to the ground).

For the purposes of this section, aerobatic flight means an intentional maneuver involving an abrupt change in an aircraft's attitude, an abnormal attitude, or abnormal acceleration, not necessary for normal flight.

If you think it fits under this definition the pilot is also in breach of 91.303

No person may operate an aircraft in aerobatic flight—
(b) Over an open air assembly of persons;
(e) Below an altitude of 1,500 feet above the surface;

I would consider a backyard party (as described in the video description) as an open air assembly of persons and he is clearly below 1500 ft.
The Counter Point: While the above points make a pretty solid case for the FAR's broken in the video, in theory if the maneuver is pre agreed upon, planned out, and executed as planned it may not be considered reckless. In the end of the day as a pilot you live at the mercy of the FAA and their decisions. In this case I would be most worried about that guy running into the propellor. I'm sure things like this happen more often than not.

Makes sense to me! I'm surprised more of these people who post crazy flying videos online don't get their certificates pulled. But I suppose if the tail number is not visible then identification can be pretty difficult

I have often felt they should but there are counter arguments, ill edit my post to reflect some of the other sides of things.

authors: داود نیکخوی تنها


text:
Why do I hear the "real" engine noise only when the plane is on the runway?
I understand that (from other answers) planes taxi using engines only. But, when I'm a passenger, then why do I hear the "real" engine noise only when the plane is on the runway?
So, if planes taxi till runway using engines only, then why don't I hear that much noise until the aircraft reaches the runway?

Airplane can start moving at engine idle (not sure how many % power) and take off can be as high as 100% power

Same reason you don't hear a Ferrari idle, but its loud when it rockets down the street...

@RonBeyer: I have a suspicion that's very intentional, unlike the plane. Ferrari's aren't even that bad. Loud cars have turbo's which at high RPM's dump excess pressure into the exhaust, but Ferrari isn't a big fan of turbo's.

@MSalters Jet engines are compressors that dump excess pressure into the exhaust, and planes are intentionally quiet at idle, there are noise restrictions around many major airports. In fact many aircraft can't take off at full power because of noise restrictions, so there is a big push to make them quiet. If you see the engine nacelles of newer aircraft, the chevrons at the back are specifically to reduce noise...

When you have the thrust levers of, say, a 747 all the way back to idle, the airplane still has enough power to move. In fact, you will have to use the brakes to keep it from taxiing too fast. If you didn't use the brakes, it would finally accelerate to somewhere around 45 knots or so, far too fast for taxiing, but much too slow to take off. At the idle power setting, relatively little noise is produced by the engines.
To take off, if the 747 were at max gross, you would have to accelerate to around 180 knots. That would require a power setting approaching the maximum, depending on the length of the runway. The noise produced by the engines is relative to the amount of power they're producing. Hence, taxiing at idle produces little noise relatively speaking, on the runway taking off a whole lot of noise.

As an engineer, I strongly suspect the amount of noise is NOT proportional to the amount of power. Noise is an inefficiency, and there's quite some engineering done to reduce it, but you'd focus on the most frequent power setting. Full power just isn't that frequent.

@MSalters I would read "A is proportional to B" in a vague sense of "A increases with increasing value of B"... :) But you're right, it is an imprecision.

@MSalters You are certainly correct insofar as the engineering and mathematical sense of the word, and I have changed it to "relative". However, for a non-technical audience, which I believe would include the person asking the question, my thought is that using "proportional" as in "the punishment should be proportional to the crime" would be appropriate.


text:
Is flight data recorder erased after every flight?
Flight data recorders store massive amounts of data per flight and despite improvements year on year with data storage as with Moore's law, carrying larger and larger amounts of data can become expensive, through larger hard drives and the extra weight.
So, is a flight data recorder erased after every flight? If so, after how long and by whom, is it automatic on landing, engine shutdown or it's one of the pilots procedures on landing?

"larger and larger amounts of data can become expensive, through larger hard drives and the extra weight."  Patently false.   Standard 128GB microSD flash cards are cheap, have massive storage, and weigh nothing.

Aparat from the mandatory crash-proof FDR, there are WiFi data recorders (WQAR) that are just downloaded at the airport, data continue to live on the ground. Other just use optical media to store Tb of data (related).

I don’t feel Moore‘s law is applicable here, as cost would be prohibitive when attempting to certify aviation hardware (which has completely different reliability, environmental and robustness requirements) at the same rate as consumer hardware is developed.

@abelenky Standard mSD cards do not survive the washing machine let alone 4km under the sea in salt water. Nor do they fare well to fire.

@Aron I think the implication is that if we can fit 128GB on a thumbnail sized chip, we don't need to worry about "size and weight" of additional storage.  Just harden your solid state storage and you're done.  You're not adding additional drives or making a bigger tape these days.

@CptReynolds exponential divided by constant factor is still exponential.

Don't forget Wirth's law when mentioning Moore's law: the amount of data that should be stored scales with the place available to store data.

@Aron Nor does any hard drive, so that's a silly thing to say. The reason these things survive such extreme conditions is entirely down to the casing. And in point of fact, SSDs are way more robust to impact and temperatures than any hard drive.

Is there a related question here about what stops a flight recorder from running on, if it happens to still be connected to battery power for 25 hours after a crash ?

My point is that mSD cards aren't archival quality storage devices. Can you ensure that the quantum tunneled charge on 9nm process floating gates can maintain their charge over a period of 2+ years in hostile environments? The data integrity of flash is terrible.

@abelenky On a typical flight a Dreamliner will record about a half a terabyte of data: If this data is not erased over the life of the aircraft, the aircraft will only have space to fly with the last 128 GB SD card.  Moores law into perspective replacing the 128gb SD card with larger and larger SD cards of the same size is is cheaper more expensive than simply deleting useless data.  Rather replace it every 4 or 10 years., perhapls in 20 years time one would store 2048 TB of data on an sd card the same size and weight.

Flight data recorders have changed over the years and evolved to what they are today. Modern recorders are recording up to 88 parameters. The storage of the recorder is dependent on the range of the aircraft. Early recorders were using a circular tape that ran through the recorder. E.g. loop recording all the data and automatically overwriting the oldest data on the tape.
The recorder of a Boeing 777 is based around modern solid state storage, capable of recording up to 25 hours continuously. Modern flight recorders are still recording continuously, so after the initial 25 hours, the storage is full. It will then start overwriting the oldest datablock stored. This ensures that you will always have the last 25 hours of data before a crash available for research.
The following quote comes from AERO Magazine Issue 02 - Spring 1998:

Flight data recorders were first introduced in the 1950s. Many first-generation FDRs used metal foil as the recording medium, with each single strip of foil capable of recording 200 to 400 hr of data. This metal foil was housed in a crash- survivable box installed in the aft end of an airplane. Beginning in 1965, FDRs (commonly known as "black boxes") were required to be painted bright orange or bright yellow, making them easier to locate at a crash site.
Second-generation FDRs were introduced in the 1970s as the requirement to record more data increased, but they were unable to process the larger amounts of incoming sensor data. The solution was development of the flight data acquisition unit (FDAU).
As shown in figure 2, the FDAU processes sensor data, then digitizes and formats it for transmission to the FDR. The second-generation digital FDR (DFDR) uses tape similar to audio recording tape. The tape is 300 to 500 ft long and can record up to 25 hr of data. It is stored in a cassette device mounted in a crash-protected enclosure.
FAA rule changes in the late 1980s required the first-generation FDRs to be replaced with digital recorders. Many of the older FDRs were replaced with second-generation magnetic tape recorders that can process incoming data without an FDAU. Most of these DFDRs can process up to 18 input parameters (signals). This requirement was based upon an airplane with four engines and a requirement to record 11 operational parameters for up to 25 hours (see "Parameters Explained" below).
Another FAA rule change that took effect October 11, 1991, led to the installation of digital FDAUs (DFDAUs) and DFDRs with solid-state memory on all Boeing airplanes before delivery. This FDR system was required to record a minimum of 34 parameter groups. The DFDAU processes approximately 100 different sensor signals per second for transmission to the DFDR, which uses electronics to accommodate data for a 25-hr period.
Today all Boeing current-production models use DFDR systems, which will store 64 12-bit words per second (wps) over a 25-hr period in electronic memory. At the end of the 25 hours, the DFDR will begin recording the most recent data over the oldest data. No tape removal is required with these systems. Each of these systems on every Boeing model (except the 777) have at least two data frames that are transmitted from the DFDAU to the DFDR (see "What Is a Data Frame?" below).
These separate data frames accommodate the different regulatory agency requirements. A 128-wps DFDR was available for the Boeing 777 and MD-90, allowing the development of one data frame that incorporated all regulatory agency requirements and that required operators to develop only one data frame decode algorithm. "How a FAA Rule Is Changed", below, explains the basis on which the FAA may propose rule changes.

Source

Makes me wonder what kind of ancient memory technology they are using. 64 x 12 bit words per second for 25 hours is not even 10MB.

@rghome Remember that reliability is of extreme concern, and that includes reliability after being lost in the ocean for a few years. There aren't many situations in which you'd need more than 25hrs worth of data, and 64 parameters once a second is enough to store most of what's needed.

This is interesting, but what's the answer to the question? The question is "Is flight data recorder erased after every flight?", not "How much data can an FDR hold?" The answer describes a loop, but doesn't say that the data is kept until overwritten.

@T.J.Crowder The first paragraph says, "After these 25 hours it will start overwriting the oldest datapoint." That tells us that it's not totally erased after every flight, but rather partially erased on every time interval it records a new datapoint, to always have 25 hours of recorded data.

@JoL - No, it doesn't tell me that. It tells me that if it's not erased, it will start overwriting after 25 hours. It doesn't tell me that it's not erased. (This isn't pedantry. I genuinely couldn't tell from the answer whether the common practice was to erase them or not. David Richerby's answer is quite clear on that point.)

@T.J.Crowder I see. I was looking at this question from the angle that the data needed to be erased to free up storage space, and so how is it erased? after every flight? Since "after these 25 hours it will start overwriting the oldest datapoint" solves that, I didn't see any reason why there would be any other type of erasure, and took that sentence as saying there wouldn't be. If there is any other motivation for erasing the data, I suppose you're right that this answer isn't explicit on that point.

@JoL - Fascinating, and I can totally see how you got there that way. :-)

@JoL, I clarified my answer based on your comments, I hope it is more clear now :)

@Brilsmurfffje Well, I think it was already clear to me from the beginning. :) I think T.J. Crowder just wanted a "No." at the beginning of the answer. The comments were about whether or not "after these 25 hours it will start overwriting the oldest datapoint" implied that "No". It's still implicit with the edit, but personally I think it's clear enough.

Some recorders compress data in a fascinating way that records a full data set only if significant changes occur, and deltas in between. The capacity is there to hold the mandatory 25hrs for „significant changes“ every second, but since often time is spent in cruise with little happening, you can get several hundred hours of actual data on these recorder types.

@rghome, not ancient, durable.  I bet your phone's memory card won't survive hitting a mountainside at 500 km/h, followed by sitting in a fire for several hours.

To that point, after the Lion Air MAX crash, they analyzed the data from the previous flight as well as the crash flight and found a similar problem with MCAS--and those pilots were still alive to explain how they dealt with it.

@rghome The quoted document is ancient; it dates back (unchanged!) 20 years, to mid-1999 (maybe even 1998 if you go by the copyright footer). 10 MB of solid state memory in 1999 was quite a lot! Remember, this predates USB flash drives, and even they only started at around 128 MB a year or two later. Possibly they are still "good enough" and still in use (because certifying new formats is expensive). Or we might already have something newer (apart from QARs).

It's probably relevant to add that the 88 paramenters on a per second basis are what is required by FAA regulations. In actual fact there is a lot more data stored, but that data is confidential and varies by manufacturer and model. The A388neo for example is reported to store half a terabyte per flight, which is quite a lot more than even 25 hrs of FAA regs would produce, and probably at a much greater accuracy than per second. An impact at 400kph may take far less than a second to disconnect a black box from it's sensors so a higher polling rate would do wonders for analysis.

@rghome  A standard 90 minute audio cassette holds about 2MB per side when encoded with a reasonable amount of error correction.  That's essentially the same technology used up until the development of solid state storage.  Rotating drives are far too sensitive to vibration and G forces to use in such an application. (I hope nobody was silly enough to try it anyway.)

@JoL I would genuinely expect a manual erasure at the beginning of a flight, to aid later forensics if nothing else (no point in them potentially getting confused by data recovered from a previous flight). That being said, data erasure can have a lifetime cost with some technologies. Anyway, David seems to have shown that my expectation is not reality.

@LightnessRacesinOrbit I think it would hinder forensics more than it would aid them. The bar would have to be really, really low for a forensics team to get confused by that, and the state of the plane in previous flights seems like very important contextual data to me. Some event in a previous flight could explain the state of the current flight. As to the lifetime cost of data erasure, I think in contrast to erasing at the beginning of each flight, overwriting the oldest datapoint to preserve constant time is a much simpler mechanic that makes lifetime prediction much more accurate.

@JoL: Fair enough!

I’ll have to check when I get back to work, but I’m pretty sure the 777 is up to 50 hours now. Also, as an aside, I believe ALPA has some say in how long the recording can be.

So, is a flight data recorder erased after every flight? If so, after how long and by whom, is it automatic on landing, engine shutdown or it's one of the pilots procedures on landing?

Absolutely not! Recorded data isn't just needed for flights that crash: there are plenty of cases where something bad happens in mid-air but the plane can still make a controlled landing, in one piece. Automatic erasure would mean you'd never have data from those incidents.
Rather, recordings are made on a loop. Originally, this would have been a looped tape; now it's digital memory. Once the memory is full, each new chunk of data overwrites the oldest stored data, so there is always a record of the last X amount of time.
There isn't really ever a reason to erase data from the recorder, except by overwriting it with new data. Having data from previous flights on the recorder is only a very minor inconvenience for investigators: the data is timestamped, so it's easy to extract the data they need. Not erasing the old data means that it's still there even if you only realise you want to see it after the plane has set off on its next flight. It also allows investigators to look a little farther into a plane's history and see if problems on an incident flight had also occurred on previous flights, without major consequences.

"plenty of cases": a count which probably exceeds actual crashes by at least an order of magnitude.  Given that a crash usually requires a whole series of things to go wrong (and each of those "things" usually doesn't go wrong), "we had a problem but were able to recover" is going to be much more common.

This doesn't say anything about the possibility of erasure between flights more generally, say at the beginning of a flight (and it need not be automatic). I'm a little surprised that this isn't indicated, for I would have thought that if a crash does occur you don't really want the dataset peppered with old, irrelevant information when you're trying to do forensics on a potentially damaged recorder. Then again, as I've commented elsewhere, full erasure is likely to have a lifetime cost for the device.

@LightnessRacesinOrbit Lifetime cost is far from the biggest issue. Having data from previous flights on the recorder is at worst a very minor inconvenience for investigators: the data is timestamped. And it has the (huge) advantage of being able to obtain data from a recent flight if you decide you want it after the plane has already begun its next flight. Storing data for the last 24hrs means that you might even have several days to decide "Hey, we need the data from that flight on Tuesday now that three more pilots have reported that slightly weird thing."

@DavidRicherby Okay, that seems reasonable. :) (Would you consider merging some of this to the answer? You have some great points with value here.)

@LightnessRacesinOrbit Done!

Sweet, nice one.

A good example of using previous data is the Gulfstream G-IV crash at Hanscom Field, where investigators used the data to determine that "the pilots had neglected to perform complete flight control checks before 98% of their previous 175 takeoffs in the airplane, indicating that this oversight was habitual and not an anomaly."

license: Creative Commons - Attribution Share-Alike - https://creativecommons.org/licenses/by-sa/4.0/


text:
What data does ACARS send back to base? Can it be used to track a plane?
An aircraft's Aircraft Communications Addressing and Reporting System uses line of sight HF via ground stations or satellites to communicate with its base station.
This system allows for three types of messages to be sent:

Air Traffic Control
Aeronautical Operational Control
Airline Administrative Control

Aeronautical operational control and airline administrative control messages are used to communicate between the aircraft and its base. Various types of messages are possible, for example, relating to fuel consumption, engine performance data, aircraft position, in addition to free text.

So, questions:

Can ACARS be turned off? Would this generate a warning at the base station?
Can ACARS send postion, altitude and heading information automatically?
Can ACARS be repeatedly pinged to track an aircraft's position and heading? Would this require any intervention by the pilots? (posted separately)
Is this system standard on commercial airliners?
What data do Airlines collect from the ACARS, if any at all?

anything on a plane can be turned off

ACARS can also use VHF for comms (not just HF).

Can ACARS be turned off? Would this generate a warning at the base station?

Yes, ACARS can be turned off.  See another answer of mine for more details.  Typically other systems use ACARS to send reports on a regular basis to update position and track other information, plus on an "as-needed" basis for abnormal things.  It would be up to the individual airline to look for these reports and to generate a warning if one didn't check in at the expected time, but I don't believe that they do this.  There is a lot of variation in the communication systems and they aren't 100% reliable so a lot of false alarms would be triggered.

Can ACARS send postion, altitude and heading information automatically?

ACARS itself can not, but other systems like the Flight Management Systems (FMS) or ADS-C on board the aircraft can use ACARS to send reports like this automatically, and in some cases they do.

Can ACARS be pinged to track an aircraft's position and heading? Would this require any intervention by the pilots?

Again, ACARS is simply a communication system.  A message can be sent via ACARS which will forward to the appropriate system requesting this information and have it respond.

Is this system standard on commercial airliners?

I believe that most airliners that travel over international waters have ACARS, but I'm not sure if it's a requirement or not.

What data do Airlines collect from the ACARS, if any at all?

This varies from airline to airline, but messages at the beginning and end of the flight (used to track flight time, etc.) and periodically during the flight are typical.  Usually periodic position updates and abnormal system indications are included as well.

Can ACARS be turned off? Would this generate a warning at the base station?

Everything can be turned off, especially in an aircraft. It will probably not generate a warning at the base station immediately, because long distance data comms are not always reliable. It would cause too many false warnings.

Can ACARS send position, altitude and heading information automatically?

Yes, ADS-C (Automatic Dependent Surveillance - Contract) provides such functionality over ACARS for ATC purposes. ATC have to establish the link first to get the reports automatically.

Can ACARS be pinged to track an aircraft's position and heading? Would this require any intervention by the pilots?

Using ADS-C position can be extracted by ATC, and the airline can do the same. Intervention by the pilots is not needed

Was this system installed and functional on MAS370?

Installed yes, functional I don't know.

What data does Malaysian Airlines collect from the ACARS, if any at all?

I have no idea.

ACARS does not include coordinates. It does include airspeed and altitude, as these are of interest for engine health. ACARS was functional on the Malaysian air flight, it was stated that before it went of radar, several messages were received.
A good starting point on ACARS can be found on SKYbrary.

ACARS can include coordinates. Simply said, ACARS are the SMS text messages of aviation. You can transmit position over ACARS just as you can do it over SMS text.


text:
Is it possible to ping ACARS repeatedly and track an aircraft?
This is a followup to What data does ACARS send back to base? Can it be used to track a plane?
I had asked this as a part of the earlier question, but it seems to be a large enough issue to be separate (plus no answers covered this aspect).
All electronic communication systems have low level diagnostic and channel check packages (commands). By pinging, I mean to send a system specific query message, and estimate the response time at base station or first receiver. Repeat the procedure multiple times, and calculate the response time differences. (Assumption) If the response time is decreasing, then the aircraft is moving towards the receiver, if it is increasing, then the aircraft would be moving away. Couple the time difference obtained from multiple responses, with the location of the receivers (which may be satellites or ground stations). Then, approximate the plane heading, location or speed, with reference to the receiver, and then with reference to the ground.
Would a process like this be possible with a high speed aircraft's ACARS? Are there any aspects specific to an aircraft that would make this impractical?

I would suggest editing the previous question to focus on the aspects that were answered then since you broke this out into a different question.  As it stands, I was about to close this as a duplicate.

When ACARS communicates via INMARSAT satellite (other options are VHF or HF to ground stations), the satellite can ping the receiver on the aircraft and determine the distance from the delay of the reply. The satellite is geostationary, meaning that it is a fixed point 35786 km above the earth. Based on the distance from the satellite you can calculate a circle where the aircraft must be on. This has been done for MH370.

Since the geostationary orbit is so high, a single satellite covers a large portion of the earth. Only a single satellite covered the MH370 flight.

This is the problem with "triangulation" - you need at least 3 stations receiving the signal in order to do it. One station gives you a circle (which you can reduce to an arc, given reasonable assumptions about the target, as was done here), two stations give you 2 possible points (you may be able to discard one - again by making reasonable assumptions about the target), and 3 give you a definite position fix.

@voretaq7 The problem with geostationary satellites you will always end up with 2 possible points, no matter how many you will have, because the sats are aligned on the equator. Unless you use spot beams, then you can rule out a point.

true - if all the satellites the ACARS are talking to are geostationary & aligned on the same plane (e.g. equatorial) you'll never get a proper fix - just a point in each hemisphere (equidistant on opposite sides of the plane) that you have to pick between

In theory you can triangulate from any signal that is being sent from a craft, but the big problem you'll run into with this solution is that ACARS only fires off bursts every half of an hour or if the engine trips certain parameter flags.  Again, a possibility but not horribly useful.
I suppose aircraft designers could go ahead and increase the number of pings with ACARS, but that doesn't really make a lot of sense when all aircraft are fitted with a couple of transponders and several other modes of communication (like calling the pilots via radio, for instances.)
In the end, I think the proper solution is to build a better GPS location system for aircraft.  One that pings a central system with the aircraft location repeatedly.  A purpose built system is going to be a lot better than piggybacking ACARS...

These interesting posts do not answer the question of how many pings sent from the satelite
were actually answered from the aircraft?  The publshed data only talks about the last ping. The system is said to be automated with the satelite sending queries on a periodic basis, reportedly hourly.  If each of these were in fact answered by the aircraft this would produce eight sets of data, each of which could generate an arc
delimiting possible position....basically eight concentric circles centered on the satelite
position, similar to the one published.
One of the above posts points out that such successive data would quickly reveal the aircraft's velocity vector directly toward or away from the satelite position...given the known signal times and the distance between the concentric arcs.
It would seem reasonable that one could make some assumptions about the magnitude of overall veloctiy vector...it should be a reasonable efficient cruising speed...say 400 mph...or a reasonable range.
If 8 data sets were generated one or more of the earlier sets should be close to a time
when the aircraft's position was known from radar.  Starting from that time and position one could use the actual total speed to determine distance traveled  - which would locate the two possible positions (north and south) on the next arc in temporal sequence, i.e. two possible specific locations with speed and heading at that time.  One then repeats this procedure from those positions to the next arc actual in time sequence, etc.
In the end this would produce two points, north and south, on the final (published) arc,
representing a possible northern and possible southern location as well an approximation
of the aircraft's actual tracks - either northern or southern.
These plotted tracks could be useful, especially in the northern case, to identify approximately when the aircraft might have entered a specific country's radar range.
Addendum:  This is really a question of velocity vectors.
Between any two arcs, assuming you have a position to start with, you can easily determine
the aircraft velocity vector directly toward or away from the location of the satelite projected on the earth's surface.  This velocity is a known quantity - it the distance between the two arcs divided by the time elapsed.  It is true we do not know actual speed but we could assume a cruising speed...an efficient cruising speed for this aircraft is apparently 560 mph at 35,000 feet.  So we know the magnitude of this vector (our assumption) but not the direction...northly or southerly  Given the time lapse involved one can calculate the distance the aircraft would fly in this time.  Set a drafting compass to that magnitude, mark a circle from the last known or calculated location and the two points where that circle intersects the next salelite arc are the putative new locations - one north and one south. In the end this should produce north and south limited portions of the final arc as more likely search areas.
Granted ... there could well be an error in cruising speed assumption.  One could assume an upper and lower speed and produce a range of possible locations at each arc.  As one looks at a whole series of arcs it may also be possible to adjust the assumed cruise speed and to see any changes in course direction.  If the aircarft had a distant goal it would seem important to choose an efficient cruise velocity to conserve fuel.

This would probably be a better comment than an answer.

The problem with the method that you describe is that there is no evidence that the aircraft was flying at a constant speed or in a constant direction.  Because of this, really the only ping that matters is the last one.


text:
What is the difference between directs and shortcuts in the Route Availability Document?
I am studying about directs and shortcuts in aviation. While flying, an airplane can move from an airway to another by using directs or shortcuts.
What I want understand is the difference between directs and shortcuts.
I know some of the information is contained in the RAD (Route Availability Document) but I don't understand if contains infos about direct or shortcuts or both.

A shortcut is a deviation from the filed flightplan given to an aircraft by ATC during the flight, if traffic and other factors permit. A flight crew cannot expect to get any shortcuts, so they cannot plan for it.
Routes in the RAD are flightplannable routes. If a direct route is available in the RAD, it can be used when filing the flightplan, prior to the flight. This allows airlines to plan for the shorter route, thus allowing them to bring less fuel and advertise a shorter flight time.


text:
What is the difference between Flight Test and Test Flight?
What is the difference between Test Flight and Flight Test?
Are they the same thing or synonymous?

Flight testing is the process (usually involving a number of test flights) by which the capabilities and performance of and aircraft (usually a new one or one which is substantially modified) are established.
Test flight refers to an individual flight which is used for testing purpose. it can be used either as part of flight testing or as a standalone for testing some minor modification.

A 'flight test' is also used when talking about assessing the pilot's competency, whereas I have never come across 'test flight' meaning the same.

They are synonymous in the business.

the other answers disagrees and gives details. could you provide something more that shows how the two are synonyms?

Well ten years in the business of designing and flight testing aircraft would be the first one.  No one at an OEM is that distinct.


text:
How to get data from Aeronautical Fixed Telecommunication Network?
I would like to download some NOTAMs and I know they can be obtained from the AFTN (Aeronautical Fixed Telecommunication Network)
.
Do you know a way to access such network and request obtain the data from it?

The AFTN is not a public access system, you'll need to use a private provider, such as RocketRoute.

So the AFTN is essentially one of the first e-mail systems, before email was even a thing. If you want to pass a flight plan, you'd select the AFTN addresses for the owners/ managers of every FIR along the route, as well as all the different offices at your destination airfield that would need to know you're coming. Unfortunately (or fortunately, depending on your perspective) unless you have access to an AFTN terminal and your AFTN address was included in the To: column, you'd have to hack the system to gain access.
And when I say "Hack", it's not necessarily in the traditional sense. The AFTN dates back to the 1950's, and maybe earlier. It is unencrypted and built on good ole' fashioned copper wire! Whilst I'm not a hacker, I believe one needs to gain physical access to the system in order to exploit it.
Nations which are considered "developed" have mostly transitioned to a digital version of the system called Aeronautical Message Handling System (AMHS). Because the AFTN copper wires are still in use in many developing nations, "bridges" are in place to digitize the analog signals allowing for interoperability between the two systems.
So the long of the short, no, you cannot legitimately access any and all AFTN messages whilly nilly.


text:
How is the Cessna 172S G1000 Electrical System powered?
Why, on a Cessna 172S, there is a positive voltage reading on the Main bus when only the standby battery switch is on? In the checklist it says

verify M BUS Volts are 1.5volts or less.

I thought that the standby battery was supposed to power only the essential bus.

Measuring volts doesn't mean you can actually power anything with it (necessary but not sufficient), and it's quite possible to measure a potential difference between two non-powered points. I'm guessing the buses are separated using diodes, and I can't speak to their electrical characteristics off the top of my head, but I'm guessing they're saying anything less than 1.5 means it's not actually shorted and no or minimal current will flow through it.

Capacitance can provide small voltages on an otherwise dead bus. Ever unplug something and see it stay on for a few seconds?

@RonBeyer: Likely the noise filter.

It would appear that there is a standby battery controller PCB.  It's important to note that M BUS VOLTS are read off the crossfeed bus as there is no main bus.  The label is a bit misleading in my opinion.  It's been awhile since I have flown a G1000 C172 but if I remember correctly you should not see 1.5volts on the M BUS VOLTS but zero.
The checklist is verifying the PCB box doesn't have a fault that will allow the standby battery to power more than just the essential bus.  Unfortunately, the POH is silent as to why this check is done.

Well, if there is voltage where it shouldn't be it means there is a short somewhere and it should be rather obvious a short is bad.

authors: سلمان اليافعي


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How can I go from a CPL to an A320 Rating?
For example, I completed my CPL multi and have 300 flight hours, can I do a A320 type rating and work for an airline if they allowed my to work with 300 hours?

Which country are you asking about?

US or not? Because there is gigantic difference.

This is actually 2 different questions (at least here in the US it is)

For example, I completed my CPL multi and have 300 flight hours, can I
  do a A320 type rating?

Yes you can get a type rating in any aircraft you please provided you can deal with all the requirements to do so.

and work for an airline if they allowed my to work with 300 hours?

Generally speaking no, it seems like you are asking about what is called part 121 operations here in the US. For that you will need an ATP ticket which requires 1500 hours of flight time. You may however be able to fly for a charter airline (operated under 135 regulations) but you will need to find one that is flying A320's....

A U.S. pilot with a Commercial license can get a type rating by going through an appropriate course. It isn't cheap, but it can be done.
The benefit of having the type rating with only 300 hours is probably pretty slight, at least in the U.S.  Anybody hiring into the right seat of an A320 either has their own "ab initio" curriculum, or else they're probably looking for far more experience than that.  There may be a unique job out there that is looking for exactly this sort of applicant, but it seems hard to imagine.
You might be better off saving the money until you have a line on exactly what position you're after, and you're confident that they'd hire you with 300 hours (or whatever you have by then). Who knows -- you may find someplace that will be glad to hire you to fly something else, if you'll get the training on (whatever they fly) by going to get the type rating. Having the money available to spend on the needed type rating could be a lot more useful than have the 320 type at that point.

Most training centers have a minimum 1000 hr requirement before they will train for a type rating.  It can be waived under special circumstances.

You can get a type rating with just a PPL, as long as you have a multi-engine rating(and there's ways around that too).


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Passenger hypoxia in a small plane at 11,000 feet: what is the pilot's responsibility?
An acquaintance of mine visiting western U.S. was recently a guest passenger in a small plane flying from Santa Fe, New Mexico to Colorado reaching an altitude of 11,000 feet. She related that she started experiencing hypoxia and there wasn't any supplemental oxygen available. Apparently they couldn't reduce altitude (mountains). She said that since then she has had trouble breathing, has gone for medical tests, etc.
I didn't want to be "that guy", so I didn't ask, but it occurred to me to wonder if the pilot was irresponsible in not having supplemental oxygen available. Apparently the pilot and his other passenger were from the area and acclimated to the altitude.
Since one can't just "ask" someone if they will be OK at that altitude, should the plane (pilot) have had oxygen available? In other words, is this an area of pilot responsibility?

Possible duplicate of Is flying at 14,000 MSL safe for children without supplemental oxygen?

The cut-off is 12,500 feet for the requirement of supplemental oxygen, and this one doesn't involve children, so @fooot I don't see why this is a duplicate question?

@falstro the answers provide good general advice which seems to be the same, consulting a regular doctor rather than a pediatrician, of course.

So once again we are at the community dilemma of, "should we mark duplicate answers rather than only duplicate questions?"  It is certainly related.

@RyanMortensen that's not a dilemma, that's how SE works. from the help page: The fundamental goal of closing duplicate questions is to help people find the right answer by getting all of those answers in one place. and the duplicate banner states: This question already has an answer here: [link to other question]

@Federico that question answers a different question, and is unlikely to attract answers that are specific to this question. By closing the question, you're effectively suppressing people from answering this specific question. Just because a different question has an answer that you decide apply to this question, doesn't mean there aren't other answers that fit better that are not applied to the other question. So yes. It is a dilemma.

@Federico yes, that is the goal, but there is a condition that requires it to be the same question, and not simply one that will receive related answers.  Learning whether or not 14,000 Ft. is safe for child-passengers doesn't inform me at all of whether the pilot has a duty of care for anyone's oxygen levels at 11,000 Ft.

There is no regulatory requirement for oxygen to be available for anyone on board an aircraft so long as it remains at altitudes of 12,500' MSL or less. And only the required minimum flight crew is required to have oxygen if they are flying above 12,500' up to and including 14,000 MSL' IF they will be at those altitudes for more than 30 minutes. CFR 91.211  If they were going above 15,000' MSL that would be another story.
So the short of it is, No, that pilot was not irresponsible, perhaps, maybe slightly inconsiderate, but not irresponsible.
The reason for this is the lower density of the air isn't low enough to harm the majority of passengers.  Except for extreme cases, such as those with severe and uncontrolled asthma or heavy smokers, the worst thing that would happen would be the passengers would just get sleepy and fall asleep.  This is natural, and because the body does not need as much oxygen when asleep.  For passengers there generally won't be any harm done from a mild case altitude induced hypoxic hypoxia.
And YES! You can ask someone if they will be 'OK' at higher altitudes!  Just as it is not only 'OK' but required to ask their weight for weight and balance calculations. (And quite frankly I believe most people find that more intrusive.)
In fact you should take 5 minutes to tell your passengers that the flight will be in excess of, say 11,000', that way they can be prepared for some unusual effects and not have to worry about them.  To take it a step further, remember you are the Pilot in Command and you should be aware of your passenger's limitations as that may trigger any self imposed safety limitations you have for the safety of the flight.
Now, if you just want passengers to be comfortable and/or they absolutely insist on not taking a little nap, then it is entirely up to you if you want to carry a portable aviation oxygen canister with you for your passengers.
For further information on hypoxia I would recommend the FAA's page on it and the differing effects on pilots, and by extension passengers.
Hope this helps!

Ok, thanks! It just struck me odd that my friend could find herself in a known, potentially health-threatening situation like that. I don't know all the details or what questions were asked or assurances given. It just seemed odd and (to me) potentially irresponsible that some small tank of O2 was not on board given the flight itinerary. But hey, I'm just a land crab, not a flier

In some people, especially at night, hypoxia symptoms can occur at altitudes as low as 5000 feet. Certainly as a pilot if I'm flying above 8000 feet I'd want an O2 meter to determine levels of hypoxia in myself, but passengers are a different story (they aren't flying the plane).

Classical skiing regions in europe are higher, using the term health-threatening is somewhat funny. Maybe she was just sick.

@Peter when you go skiing, the transition is slow, giving your body time to adapt (more red blood cells I think, which is why many athletes train at higher altitudes before a competition). When you fly you climb in a matter of minutes, it can absolutely be hazardous to your health, hypoxia is not to be taken lightly.

The transition-time is a point. But waiting for more red blood cells will not work, you need days or even weeks for this type of altitude training.

@falstro You have to live at altitude for weeks for your body to adapt to it. A slow drive up a mountain isn't nearly enough time to change anything, so a ski resort above 11000 is no different from that flight.

Glad to help! If I had known you were not a pilot I would have chosen a different word set to describe the different effects of altitude and the medical effects therein. If you need any additional clarification let me know.  Please let your friend know that she was not in any danger and she could have easily talked to her pilot and he/she would have explained it to save her a trip to a doctor!  As a pilot I can say, most every one of us has no problem with answering general questions about a flight like this!

Even though one can ask passengers whether they will be OK with this-or-that altitude, chances are that the passenger who'll have a problem won't have the faintest idea what they can handle if you ask them before departing. So you can ask all you want, you just won't get any wiser from the answer you get. In contrast, if you ask for someone's weight, there a good possibility that they know the correct answer. The two questions are not comparable at all.

@HenningMakholm  Just to clarify the record, I was comparing the two questions' legitimacy for the pilot to ask, not the accuracy of the information.  Also the pilot should not be looking for the passenger to know exactly their personal tolerance, rather to find out if they have severe asthma or are a heavy smoker.  This way the pilot can be more informed and make adjustments in either altitude or to carry Oxygen on a flight when they normally would not.  There's always the chance that the passenger could know their limitations and there's no downside to the pilot asking the question.


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Can a pilot transition from a localizer approach to an ILS approach?
I was recently looking at the approach to RWY 8L at Honolulu, Hawaii (PHNL).
Looking at the approach IAFs, I see the LOC RWY 8L approach has many different options, and has an intercept altitude at 2,300 ft. The ILS RWY 8L approach has three IAFs but none are south of the airport, and the glide slope intercept altitude is 2,700 ft.
In the scenario where a visual approach isn't appropriate and an ILS may be necessary, are there procedures/rules in place for a pilot to transition from the LOC approach to the ILS with glide slope once they are lined up? I know the LOC intercept is at a lower altitude, so can a pilot just intercept the glide slope from that altitude or are the two procedures incompatible and radar vectors are required to line the pilot up for the ILS?
I'm looking specifically at the JULLE5 STAR into the LOC 8L approach. JULLE5 ends at ALANA. The LOC has a IAF from ALANA, while the ILS doesn't (only BOOKE).

I don't understand your question. Transitions? The ILS has and the LOC each have three Initial Approach Fixes (IAF) to transition to the approach from the enroute environment. Levels? The ILS will get you down as low as 200' above the Touchdown Zone Elevation (TDZE), whereas the LOC will get you no lower than 500' above TDZE.

In actual practice ATC will vector arriving aircraft onto the ILS. In the case of a radar outage, most arriving aircraft will have RNAV capability and can transition from the arrival to the ILS approach via any of the three IAF, as applicable.

If you want to discuss this further you could explain your question in chat.

Note that the JULLE FIVE STAR chart says "Expect vectors to final approach course". So if you fly ILS RWY 8L, the controller apparently has to tell you how to get from ALANA to one SELIC or MAKOA, the IAFs.

@JonathanWalters yes you are correct, I read the chart and wrote the post last night, but didn't post it until this morning and didn't catch my error. Thanks! I've updated the question.

If you read the STAR, once you reach ALANA, fix, you can expect radar vectors to final approach course and clearance to fly the ILS RWY 8L.  Most likely Honolulu approach will give you vectors southwest of PHNL to southwest of MAKOA fix, then instruct you to turn right to a northeast heading to intercept the localizer and give you approach clearance.  Once you get clearance to fly the approach and acquire the localizer, you are committed to flying an ILS approach, as there are no optional LOC stepdown fixes published on this plate.  This makes the PHNL ILS RWY 8L approach rather unique as most ILS approach plates list LOC stepdown fixes and a MAP along with them.  There, the option to fly either the ILS to published DA or just fly the LOC approach to publiched MDA and MAP is up to the discretion of the pilot.  Generally speaking, most aircrews will opt for the precision ILS rather than ignoring the glideslope and flying the nonprecision localizer approach.  But that's your call as a pilot.

You can't legally switch from the LOC to ILS approach without ATC approval in this case, since they are different enough and are on different plates. However, if you're outside the FAF you can ask ATC to switch from LOC to ILS, and proceed with the ILS if approved. However, in lost comms, if you got initial approval for the LOC approach but no mentions of ILS, you can't switch to the ILS. Unless you exercise your emergency authority.

For the first part of your question you need to understand the parts of an ILS. ILS stands for Instrument Landing System.
The ILS system may be divided functionally into three parts:
   (a) Guidance information: localizer, glide slope;
   (b) Range information: marker beacon, DME; and
   (c) Visual information: approach lights, touchdown and centerline lights, runway lights
The localizer provides horizontal guidance. The glide slope provides vertical guidance, and the DME and marker beacons provide distance guidance. Notice the straight-in minimums on the ILS RWY 8L approach chart. They are 213-½ which means that an aircraft can fly down the glideslope until it is 200' above the ground. If they see the the approach light system (which in this case is a MALSR) they can proceed another 100'. If they don’t see the runway at 100' above the runway then they need to fly a missed approach.
There is actually a list of things they need to see in order to continue the approach—runway end identifier lights (REIL, the flashing strobes on either side of the threshold)
the runway (itself, the markings, or lights)
the threshold (itself, the markings, or lights)
visual glideslopes (VASI, PAPI, etc.)
the touchdown zone (itself, the markings, or lights)
The localizer approach uses the same horizontal guidance as the ILS but it does not provide vertical guidance. Notice that the straight-in minimums are 460'. That’s because the pilot is relying solely on the altimeter for vertical guidance and it is not as accurate as the glide slope.
Both approaches use the outer marker. The ILS uses it as a way to verify that the aircraft is at 1994' when it crosses the marker. The Localizer approach uses it as a step-down fix—the aircraft can begin its final descent to landing. In this approach the pilot must not descend below 2000' unless the items above are seen. At 0 DME they begin the missed approach.
Most aircraft that are equipped with IFR instruments will have a glideslope. However, it may be inoperative or the glideslope at the airport may be inoperative in which case they would fly the localizer approach.
I don’t know if they do it at this airport, but often airports with two parallel runways will use the localizer approach to one runway with a side-step to the other. If ceilings are high enough, they may do it here.

This is a nice description of ILS, but I am pretty sure OP understands all of this and it is absolutely irrelevant to the question, which is not about minima and missed approach, but instead about why the initial approach fixes differ (look at the linked charts!), whether the segment from one approach can be used to get to the IAF of the other when the STAR does not lead all the way there, or what can be used instead.

@JanHudec bingo, thanks for clarifying my words better than I could!

Sorry about the confusion. I’m still having trouble understanding questions when the OP is not a native speaker.

This is a good answer which was initially provided to the original question which was fairly incomprehensible and seemed to display a significant lack of understanding of the ILS.


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Are large passenger aircraft steered during taxi by changing the angle of the front landing gear?
When moving to and from the runway, does a large passenger aircraft turn by changing the thrust difference on its side engines, or by turning the front landing gear to a different angle? If it is by turning the front landing gear, through what device does the pilot control the angle?

And sometimes the nose gear jams at some awkward angle at takeoff and can't be retracted and is unusable for landing. This leads to some spectacular fireworks that makes the evening news, and some aircraft damage, but rarely injury.

During taxiing aircraft turn using their nose wheel.
The nose wheel is usually hydraulically controlled. The pilot operates it through a tiller. The nose gear can rotate usually quite far, sometimes to almost 90 degrees.
At high speeds, directional control is achieved using the rudder pedals. The nose gear is often linked to the rudder pedals, however the maximum rotation is limited. The nose gear steering does not exactly match to the the rudder steering at all speeds. At low speeds the rudder is ineffective so the nose wheel steering is dominant. For sharp turns the tiller is always used because of the limited rotation by the pedals.

A320 Nose wheel tiller

B747-400 Nose wheel tiller

Also, although the tiller is named after the device on a boat, physically it is moved nothing like it! In Boeing aircraft, typically it rotates like the arms of a clock, with "straight ahead" being sprung to return at 12 o'clock, and "90º" left or right at about 7 or 5 o'clock. Airbus (and other) aircraft typically have it mounted about a shaft, rotating like a corkscrew or wrench.

Does the tiller automatically reposition itself to the straight position, or does the pilot have to straighten it?

While turning the nose gear is the primary means of turning while taxiing, differential thrust can be used when necessary. Offhand I can think of three instances where differential thrust should be used on an airplane such as the 747:

If for whatever reason you are taxiing very slowly, and you're on narrow taxiways and need to make a 90 degree turn, you'll need differential thrust to keep the airplane from stopping in the turn.
If your center of gravity is near the aft limit, there won't be much weight on the nose gear, and it might start skidding when you try to turn significantly without differential power.
If the asphalt is hot and/or you're on reverted rubber, the nose gear won't have a lot of traction, and you really need to think about using differential power. I almost slid off a taxiway at Jeddah one day in such a situation even though my taxi speed was only around 8 knots. A general rule of thumb for the 747 in making 90 degree turns was to have your taxi speed down to 10 knots or less, otherwise the nose wheels might just skid.


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Why were there pneumatic headphones on airliners in the 70's and 80's?
I remember listening to the on-board program with headphones that consisted of hollow hoses as a kid. You plugged them into small holes in the arm-rests. The program was the same for everybody.
Why was the system in place? Why was it phased out?

Do you really want to listen to the drone of the engines for 3.5 hours?

Why? Because passengers are people too, and appreciate some entertainment while crammed into a noisy uncomfortable seat between two other smelly people and only a tiny window to look at the view. And phased out? Quite the opposite, in-flight entertainment systems have simply changed technology.

Why was it pneumatic? Presumably because that was much cheaper. (incidentally, "pneumatic" is better than "acoustic" for the title. as all headphones are acoustic).

Yes, pneumatics used to be cheaper and more reliable, nowadays it is the opposite thanks to  improvements in digital technology. And the same holds for audio quality, I think. (For a system with a large number of headphones.)

possible duplicate of Why do entertainment system headphones on aircraft have two pins?

This is a possible duplicate to "Why do headphones have two pins?".

@SentryRaven I don't think this is a dupe. The excellent answer to that question doesn't really touch on this one.

Well, the rubber hoses themselves were used instead of traditional electromag transducer headphones for two main reasons; first, the hoses were much cheaper than a decent pair of traditional headphones at the time, and to an extent they're washable, so airlines could provide a pair for everyone at a much lower pricepoint than traditional headphones. Second, the hoses were more or less useless without the driving system aboard the aircraft, largely removing the incentive for passengers to walk off with them, again reducing costs of providing the system to passengers. The system was phased out in favor of simple 1/8" stereo jacks at each seat in the '80s and '90s as portable audio became mainstream, and as airlines looked to dramatically slash costs in the face of deregulation beginning in 1978. Economies of scale meant that buying cheapo Walkman-style headphones in bulk became cheaper than maintaining the aging pneumatic systems, and the electric-based system was more reliable and had several advantages (such as volume control for each passenger, and if standard 1/8" jacks were used, the ability for a savvy flyer to bring their own, nicer pair for use on the flight).
As an aside, this pneumatic audio system is still used today for a very different purpose; newborn hearing screenings. A pair of flaps with a mild adhesive are stuck to baby's ears, then hoses lead back to a finely-calibrated audio system coupled to an EEG. Audio is played and the EEG is monitored to detect the response to the sound in baby's brain. The hose system is used because it allows the expensive, fine-tolerance part of the audio system to be reused from test to test, while the hoses themselves are disposable and (as hospital equipment goes) fairly inexpensive.

I'll answer your second question first that why pneumatic headphones were phased out.
The simple answer would be that a better technology was available, and affordable on commercial level. Questions like DVDs replacing CDs, or why 3.5" floppy disks replacing their 5.25" counterparts, DSLRs replacing SLRs are all on the same lines.
Electric headsets have several advantages in terms of quality of audio, durability, lower cost of production and longevity.
Why pneumatic headphones, or as a matter any headphones, were used in an airplane relates to why in-flight entertainment was places in airplanes? By 1960s, in-flight entertainment was getting popular and airlines were using it as marketing tool. As this evolved, headphones (pneumatic at the time) jacks were added for each passenger so that if a passenger doesn't want to be entertained, can choose to do so.

Though this is not directly related, this question What was the inflight entertainment in the early seventies? has some excellent information about in-flight entertainment, which does talk about pneumatic headphones too.